Self-cooling water bag



April 19, 1949. F. H. wENzEL ETAI..

SELF- COOLING WATER BAG Filed April 23, 1945 LL 5 i n @2N M NE e TW. N.FT EHN Q. H /voa F Patented Apr. 19, 1949 SELF- COOLING WATER BAG Fred H.Wenzel, St. Louis, and Herman F. Wenzel, Fenton, Mo.

Application April 23, 1945, Serial No. 589,932

3 Claims. 1

The present invention relates to a4 water bag, and more particularly awater bag made of fabric material designed to have a controlled oozingor exudation of water therefrom, in restricted quantities, designed-toprovide evaporation that will cool the contents of the bag.

This application is a continuation in part of application Serial No.412,158, filed September 24, 1941, now abandoned, for Water bag andmethod of making same, by the applicants hereof.

Heretofore, water bags adapted to keep water cool through an evaporationprocess have been made of flax imported from Europe. The applicants havedeveloped a water bag of treated cloth and a novel method of preparingthe cloth to replace the flax water bags.

Therefore, it is an object of the present invention to provide a novelmethod of treating nonilax cloth to render it suitable for use in makingwater bags. y

Another object is to provide a novel method of treating non-flax clothto produce a cloth which is adapted to permit seepage, for evaporationpurposes, for maintaining water in a bag constructed of the materialthereof at a cool temperature.

Another object is to provide a novel water bag of treated non-flax clothwhich permits seepage for evaporation purposes at warm temperatures,above that of the water, to maintain the water therein at a cooltemperature.

Another object is to provide a novel method of treating cotton cloth torender it suitable for water bag construction.

Specifically, an object of the invention is to provide a water bag madeof readily available and relatively inexpensive fabric, such as cottonmaterial, treated so as to obtain the characteristics exhibited by flaxwhen used for this purpose. Particularly, it is an object to provide awater bag, made ofinitially porous material, with an impregnator, torestrict the exudation of water therethrough to amounts giving a lm ofmoisture on the outer surface, particularly where the film supplieswater for evaporation, without excessive dripping, that reduces thetemperature of Athe water in the bag toward wet bulb temperature.

It has heretofore been known that flax has the peculiar property, whenmade into a water bag, of providing a restricted seepage of waterthrough the bag to the outer surface thereof, that supplies a. wetnessto the fibers, and, at atmospheric conditions representing a mean ofthose in which it is designed for use, a film of water 0n said outersurface.

Such flax bags have the foregoing property only after they have beenwater soaked for long periods, such as 24 hours. Also, they are subjectto becoming musty, giving a flavor and aroma to the .water that isundesirable. Flax is not a readily available material, and is relativelyexpensive, so that its use is further restricted.

Efforts have been made for many years to use domestic and inexpensivecloths for purposes such as water bags. The efforts have beenunsuccessful up until the present invention becauseof the inability tocontrol the seepage of Water through the material. It has been found bythe present applicants that cotton and like non-flax materials can beprepared with the addition of preparations that control the interstitialspaces, between the fibers and between the threads, in such wise as toget a regulatable exudation of moisture therethrough. l

Water bags must'have a seepage at least substantially within the rangeof possible evaporation from the outside surfaces of the bag. If morewater than this seeps through, it will not evaporate, but will drip fromthe bag as wastage, and also as a possible nuisance to the user. If thebag material, however, is so tight that no seepage at all occurs, thenno cooling can take place.

As noted, the purpose of the present invention is to impregnate non-flaxmaterial, and particularly cotton, such as cotton duck or twill, with amaterial that tends to fill the interstitial spaces of the fibers, todelimit the passage of water through the ber to controlled quantitiessubstantially within the range of possible evaporation from the outersurfaces of the bag.

In the drawing:

Fig. 1 is a side elevation of a water bag fof the' present invention; Y

Fig. 2 is a somewhat schematically shown greatly magnified portion ofthe fabric of the bag of Fig. 1.

The bag 5 is shown as having a top closure and handle combination shownat B, and a conventional spout with closure; shown at 1. Neither thehandle 6 nor the spout 1 is part ofthe invention claimed herein.

The bag 5 is made of impregnated fabric, which consists ofa fabriccontaining the solid residue of a dispersion (as will appear) resultingfrom the application of the dispersion tothe cloth and the eliminationof the liquid substance therefrom.

One particular method of accomplishing this is by impregnating cottonduck with paraffin derived from a water emulsion of parailin. Theemulsion may be prepared from paraffin, water.

and one of the familiar water soluble emulsiflers. A wax proportion of12%% has been found satisfactory for many atmospheric circumstances.

A cold bath of this parailin emulsion may be used, as the impregnationtakes place as well from a bath that is cold as from one that is warm orhot. The emulsion may be placed in a container wherein there are clothrollers, and the cotton cloth run through the emulsion over the rollers.Thereafter it is hung up to enable the water to evaporate therefrom.When the water is evaporated, the impregnated material may be re-rolledfor convenience in handling, and then cut and sewed into bag form, withproper outlet.

Fig. 2 illustrates, in somewhat schematic manner, a magnified section Iof a bag impregnated with the residue of the paramn wax emulsion. Suchresidue leaves a multiplicity of minute particles that adhere to andamong the fibers and threads of the fabric, and constrict the size oftheinterstices therethrough, leaving only small interstices thattransmit limited amounts of liquid through the fabric. A typical cottonduck for water bags is that having a weight of about 18 ounces persquare yard, single-filled. A weight range of 14 to 24 ounces for theabove emulsion is satisfactory. Or a twill of 11.6 ounce weight isparticularly desirable. The choice of the weave is determined by certainfactors later to be described.

As suggested in the former application, the water emulsion of paraillnis the most desirable preparation for the purpose at hand. Solvents inplace of emulsifying agents have been used, of which gasoline maybementioned as typical. Thesey solvents, however, almost invariably imparta taste and a residual aroma to the material, and hence are undesirablewhere such taste and aroma are unacceptable. Also a water emulsion ismuch cheaper to use than a solution containing an expensive solvent, andthe wax-water emulsion is easy to handle.

Certain plastic materials, dissolved in conventional solvents andimpregnated into the cloth in a manner similar to the wax solutions orby painting onto the surface, with provision for the evaporation of thesolvent, may also be used. However, the results have not proved asuniform as those obtained with the parafiin-water emulsion.

It will be noticed that the impregnator materials recited are amorphous,water insoluble, and more or less pliable at ordinary atmospherictemperatures. As a result, they tend to adhere to the fibres and to beretained by them, during use of the bag, in contrast to hard,crystalline particles.

It has been found that, ideally, the amount of water seeping through awater bag should be just enough to provide the evaporation necessary topreserve the wet bulb temperature of the water within the bag. Forpractical reasons, it is, of course, virtually impossible to provide theprecise amount for obtaining Wet bulb temperature. Either some drippingoccurs, or less exudation than that required for maintaining wet bulbtemperature is provided. This is particularly true as variations in theamount of seepage through any treated material do not vary exactly aswet bulb temperature varies. Hence, the bag that is usable for certaindry and wet bulb temperature conditions and evaporation rates might notbe proper for others. A bag to be used on a desert, where the relativehumidity is very low and the dry bulb temperature very high, must have avery libture.

eral seepage in order to provide the volume of water to evaporate thatwill keep the temperature of the water approximating wet bulbcondltions. If such a bag were used under conditions of high humidity,its seepage would be so great, and so much in excess of evaporationrates, as to result in undesirable dripping from it.

However, any reasonable amount of seepage and evaporation will produce asensible lowering of temperature within the bag over that at theexterior. For instance, a certain bag, operating under dry bulbtemperature of approximately 103 F. and relative humidity ofapproximately 29.8, and losing 16.5% of its water within a period of 8hours, maintained a water temperature of 90 F. or below, the temperatureincreasing from approximately 80 to the 90 during the course oi' thelast 7 hours. Another bag, operating under identical conditions butproviding a water loss through seepage of 24.4% maintained the waterwithin the bag at a temperature of approximately the wet bulb value of78 F. at the end of 8 hours. the temperature rising from to 78 duringthe course of the last 7 hours.

Thus, the bag with the lower seepage did not4 keep the water vas cool asthat with the higher percentage of water loss, but, nevertheless, didmaintain the water more than 10 below outside temperature.

In another test, the bag in the foregoing example, having 16.5% waterloss in 8 hours, was subjected to outside temperature conditions of921/2" F. with a high relative humidity of 72%. After 9 hours, this bagshowed a water temperature of approximately wet bulb value. Hence, theseepage permitted by this particular bag was substantially ideal for theparticular wet bulb temperature conditions of the second test.

The result of the tests that have been made show that, for low humidityand high temperature conditions, the bag must be made to have a highseepage rate; whereas, for high humidity, the seepage rate will be lowerbecause of the low er capacity of the atmosphere to take up mois-Obviously, if the moisture cannot be absorbed as evaporation, it willdrip ot! and be obiectionable in the use of the bag.

The control of the water seepage is obtained by varying the size of thepermitted interstices in the cloth of which the bag is composed. With avery tight weave of cotton cloth, such as the 18 ounce duck heretoforementioned, for example, a 121/2% wax emulsion gives the aforementionedbag having the 16.5% water loss in 8 hours, at 103 F. dry bulbtemperature and 29.8% relative humidity. A twill bag, however, immersedin the same emulsion, provides greater seepage of water. The twill bag,therefore, would be more acceptable in localities where there is a highevaporation of moisture; whereas the duck bag would be emlnentlysatisfactory in places of high humidity where the evaporation capacityis low.

For given zones or areas, ranges of conditions can be observed and madethe basis for the manufacture of bags used therein. To illustrate, adesert style bag may be manufactured having a high rate of seepage foruse in conditions of high temperature and low humidity. On the otherhand, a bag may be made for use in such climates as certain parts ofFlorida where the humidity rate is very high, and, consequently, theevaporation rate very low, this bag having small inter-y stices and lowseepage rate.

The seepage rate may be controlled to a large degree by adjusting thepercentage of wax in the emulsion. It also may be controlled by varyingthe Weave of the cloth used, so that it becomes less'penetrable bywater. Also, the diiferent types of ller material or impregnator varythe seepage rate.

In summary, it may be said that as an overall matter the seepage must besomething from a visible seepage up to a condition just short of whereexcessive and undesirable dripping comes from the bag. An adequate bagmay be obtained hy applying' a simple observation test, under theapproximate mean conditions of use, to see Whether there is anyevaporation at all, as a minimum limit, or whether there is excessivedripping as a maximum limit.

, A normally good bag, tested at mean atmospheric conditions of use,will show a thin iilm of water over its outer surface, preferably withno dry spots indicating areas of irregularl exudation, Without any morethan a slight dripping. On the other hand, the most satisfactory bagwould be determined mathematically for the conditions under-which it isto be used, and manufactured to give an amount of evaporationapproximating that required for withdrawing the amount of heat tomaintain wet bulb conditions of the water contained.

What is claimed is.

1. A self-cooling container for Water or other liquids comprising aliquid-holding bag at least one wall of which is made of fabric havingsmall openings large enough to permit seepage therethrough but inuncontrolled quantity, means to control said seepage comprising animpregnator which consists of the solid residue resulting from theevaporation of a liquid dispersion of a substance that is amorphous,Water insoluble, relatively hard atI low temperatures, relatively softat high temperatures, and increasing in softness as the temperaturerises, the impregnator being distributed throughout the fabric of the.bag to constrict the size of said openings thereby to control the rateof seepage therethrough, the size of said openings being so controlledby the impregnator as to transmit water through the fabric to form afilm on the exterior of the bag and to keep the water transmission toamounts substantially within the evaporation capacity of the atmosphereas the condition ofthe atmosphere changes, whereby the evaporation ofthe water from. the film will draw heat from the liquid within the bagand restrict rise in temperature of said liquid. l

2. A self-cooling container for water or other liquids comprising aliquid-holding bag at least one wall of which is made of fabric havingsmall openings large enough to permit seepage therethrough but-inuncontrolled quantity, means to control said seepage comprising animpregnator which consists of the solid residue of a dilute emulsion ofan amorphous, Water insoluble substance, said substance being relativelyhard at low temperatures, relatively soft at high temperatures, andwhich increases in softness as the temperature rises, the impregnatorbeing distributed throughout the fabric of the bag to constrict the sizeof said openings thereby to control the rate of seepage therethrough,the size of said openings being so controlled by the impregnator as totransmit Water through the fabric to form a film on the exterior of thebag and to keep the water transmission to amounts substantially withinthe evaporation capacity of the atmosphere as the condition of theatmosphere changes, whereby the evaporation of the water from the ilmWill draw heat from the liquid within the bagr and restrict rise intemperature of said liquid. l

3. A self-cooling container for water or other liquids comprising aliquid-holding bag at least one wall of which is made of fabric havingsmall openings large enough to permit seepage there--v through but inuncontrolled quantity, means to control said seepage comprising animpregnator which consists of the solid residue of a dilute emulsion ofa paran wax, the impregnator being distributed throughout the fabric ofthe bag to constrict the size of said openings thereby to control therate of seepage therethrough, the ysize of said openings being socontrolled by the impregnator as to transmit water through the fabric toform a film on the exterior of the bag and to keep the watertransmission to amounts substantially within the evaporation capacity ofthe atmosphere as the condition of the atmosphere changes, whereby theevaporation of the water from the film will draw heat from the liquidwithin the bag and restrict rise in temperature of said liquid.

FRED H. WENZEL.

HERMAN F. WENZEL.

REFERENCES CITED lThe following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number

